With the increasing demands of users on bandwidth, a conventional broadband access system that uses copper wires gradually faces a bandwidth bottleneck. At the same time, the optical fiber communications technology that has huge bandwidth capacity becomes increasingly mature, and the application cost is decreased year by year. An optical fiber access network, for example, a passive optical network (PON), becomes more and more competitive for the next-generation broadband access network. Currently, in many solutions of an optical fiber access network, the wavelength-division multiplexing passive optical network (WDM PON) technology receives much concern due to its advantages such as larger bandwidth capacity and a communication manner that is similar to point-to-point manner and ensures information security.
Generally, a WDM PON system mainly includes multiple optical line terminal (OLT) transceiver modules located at a center room and multiple optical network unit (ONU) transceiver modules located at the client side, where the OLT transceiver module and the ONU transceiver module generally adopt a laser diode (LD) as a light source. Different ONU transceiver modules need to adopt different communication wavelengths (λ1, λ2, . . . λn) to perform communication with corresponding OLT transceiver modules, thus the WDM PON system requires that the laser diodes of different transceiver modules are capable of emitting optical signals of different wavelengths respectively. In order to implement colorlessness of light sources, reflective semiconductor optical amplifiers (RSOA) are proposed in the field to be the laser diodes, and seed light are injected to the RSOAs, so that different RSOAs are locked to different wavelengths respectively.
However, similar to other semiconductor devices, the conventional RSOA has a problem of rather obvious temperature sensitivity. Specifically, with change of temperature, the RSOA may generate phenomena such as gain spectrum drift and drop of a gain peak value. For example, with increase of temperature, the gain peak of the RSOA may drift toward a long wavelength direction (a temperature drift coefficient is about 0.5 nm/° C.), and a gain peak value drops at the same time. The changes of the gain directly influence the performance of the WDM PON system, for example, the changes of the gain may result in problems of the WDM PON system such as reduction of signal extinction ratio, shortening of transmission distance, and an increase of bit error ratio.